Hydraulic pump



'/Jenz.

Oct. 20, v1959 H. c. JENNINGS, JR 2,909,123

HYDRAULIC PUMP y Filed Nov. 25, 1957 www 23% BY @7m/5; )www United States Patent O HYDRAULIC PUMP Harry C. Jennings, Jr., Los Angeles, Calif., assigner to Everest & Jennings, Inc., llos Angeles, Calif., a corporation of California Application November z5, 1957, serial No. 698,746

s claims. (c1. s- 40) This invention relates to improvements in hydraulic pumps.

Explanatory of the present invention, it has been proposed to provide an invalid wheel chair with a vertically adjustable seat which can be raised and lowered by a hydraulic ram which is actuated by a manually operable pump that pumps liquid rom a liquid reservoir in to the ram to elevate the seat and which can release liquid from the ram to be returned to the reservoir when the seat descends. Other chairs, such as for example dental chairs, barber chairs, and the like, employ a similar principle of raising and lowering the seat. It frequently is desirable that when the seat has been elevated to the desired height that the handle which operates the pump can be swung or moved to a suitable inoperative position which will not be in the way or interfere. It is also desirable to employ the same pumping mechanism for the purpose of elevating the seat and also to eect a release of liquid from the ram back to the reservoir and to have the structure so arranged that movements of the operating handle to an inoperative or concealed position be accomplished while the pump is operating on its intake stroke so that these movements of the handle to the inoperative or concealed position do not affect or alter the height of the seat.

It is further desirable to have the release of the liquid from the ram back to the reservoir be accomplished while the piston of the pump is moving on its intake stroke so that even though the ram may have reached its fully extended position during a partial working stroke, that nevertheless, release of liquid from the ram back to the reservoir can be accomplished by moving the piston of the pump in the direction of its intake stroke.

It is therefore an object of the present invention to provide an improved pump which will meet all of the necessary requirements and above outline desiderata.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure 1 is a sectional view through the improved pump, the piston being shown in-that position wherein a release of liquid from the ram back to the reservoir is being permitted;

Fig. 2 is a similar view showing the piston on the start of its working stroke; and

Fig. 3 is a similar view but showing the piston at the completion of its working stroke.

Referring to the accompanying drawing wherein similar reference characters designate similar parts throughout, the improved pump comprises any suitable structure providing a cylinder generally indicated at 10. This cylinder is slightly larger at one end as indicated at 11 than adjacent the other so as to provide a shoulder 12. A piston rod 13 that is axially reciprocable extends into the cylinder through the open end thereof and a sealing means closes the small end of the cylinder around the piston rod. This sealing means is shown as consisting of chevron y, amarga Patented Oct. 20, 1959 packing 14 positioned against a plate or washer 15 that is seated on the shoulder 12. Y

The opposite end of the cylinder is closed as indicated at 16 except for an inletV 17 that receives liquid from a source of supply such 4as a liquid reservoir, not shown. The outlet from the pump is indicated at 18 which leads to a hydraulic ram (not shown). Above the seal 14 there is a sleeve 19 which lits the larger end of the cylinder but which is spaced from the piston rod 13. Chevron packing or the equivalent indicated at 20 is disposed above this sleeve and is coniined in place by a threaded closure or nut 21. l

The end of the piston rod is hollow as indicated at 22 and isY internally threaded to receive a hollow screw 23, the head of which is indicated at 24. A piston 25 is formed by a ring of rubber or rubber-like material which is coniined between opposed washers 26 `and 27 that are clamped towards each other by tightening the screw 23 in position.` The piston rod 13 and screw 23 may be considered collectively as the piston rod which has a passage 28 extending longitudinally or axially therein. Y This passage i's open as indicated at 29 to the inlet 17 and is open through the ports 30 to the space between the piston and the sealing means 14 which space 31 may be regarded as the working cylinder. The passage is also open through port 32 to the space between sleeve 19 and the piston rod and ow is permissible through the port 33 and groove 34 to the outlet 18. The screw 23 is also externally grooved adjacent ports 30 so that these ports are always open between the working cylinder 31 and the passage 28.

Seats 35 and 36 are formed in the passage on opposite l sides of the ports 30 for two check valves 37 and 38, respectively. A coil compression spring 39 is disposed between the check valves and surrounds a lioating release pin 40 that is in the passage 28. A coil compression spring 41 is compressed between the body of the piston rod 13 and the ball check valve 37. In the closed end 16 of the cylinder 10 there is mounted a stationary release pin 42 which is engageable with the check valve 38.

The piston rod 13 is axially reciprocated by any suitable mechanism (not shown) such as for example a hand lever. When it is desired to pump liquid from the inlet 17 through the outlet 18 and to the Vram to elevate the seat, the piston rod 13 is reciprocated between the two positions shown in Figs. 2 and 3 which may be regarded as being the length of the working stroke. If the piston rod 13 is moved upwardly from the position shown in Fig. 2, liquid is drawn into the cylinder 10 through the inlet 17 beneath the piston. Liquid which may be in the working chamber 31is compressed between the piston and the sealing' means 14 and is expelled through ports 30 through passage 28 and upwardly beneath the ball check valve 37, unseating this valve and flowing through ports 32, 33, groove 34 and through the outlet 18. When the piston rod moves in the opposite direction the partial vacuum created in the working chamber 31 causes liquid taken into the cylinder through inlet 17 to unseat the ball check valve 38 and to be drawn through ports 30 into the working chamber. During this intake stroke of the piston the ball check valve 37 Yremains seated and consequently, the 'ram remains in its elevated position during the intake stroke. When the piston reaches approximately the position shown in Fig. 2, it may be reciprocated in the opposite direction. That is, from the position shown in Fig. 2 to the position shown in Fig. 3 and an additional charge of liquid will be forced out of the outlet 18 as-'previously explained.

When it is desired to lower the seat by releasing liquid from the ram in a reverse direction through the outlet 18 and through the passage 28 the piston is moved into the position shown in Fig. l, that is into a position exceeding the normal length of the intake stroke. When this occurs the ball check valve 38 is carried into engagement with the end of the stationary release pin 42 so that the ball check valve is unseated thereby. The unseated ball check valve engages the oating release pin "40 and causes it in turn -to unseat the ball check valve :37. With both check valves simultaneously open flow from the ram can reversely take place through the pump from the outlet 18 to the inlet 17 and the seat can consequently descend.

It will be noted as an opening of the valves takes place at the conclusion of the intake stroke that if the ram supplied by outlet 18 should become fully extended when the piston has completed only part of its entire Working stroke that nevertheless a release of Huid from the ram can be accomplished .by merely moving the piston through its intake stroke and lin excess yof it. The rate of descent of the `seat or the rate at which Iliquid is allowed to be returned from the ram :can be 4governed or regulated to a large extent by the amount of-clearance at 29. Thus, if a slow descent is desired this `clearance should be made relatively small and this can be easily accomplished by substituting a slightly larger stationary release pin for the release pin 42 that is illustrated.

It will be appreciated from the above-described construction that the improved pump is of relatively simple construction having few moving parts and is quite positive in its action. During working strokes of the .piston liquid can be pumped from the reservoir to the ram. On the other hand, when it is desired .to release liquid from the ram back to the reservoir this can be accomplished by merely moving the piston rod to a position beyond the end of its normal intake stroke. Whenever the ram has been pumped up to the desired elevation reciprocation of the piston rod 13 is discontinued and the piston may be returned to the start of Iits .power stroke. During this return there is no reverse ilow of fluid through the outlet 18. Consequently, the operating handle for the piston rod 13 may at all times be shifted to an inoperative .position without involving a raising or lowering of the rarn as an incident thereof.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as deiined bythe appended claims.

I claim:

l. A pump comprising a cylinder, a piston reciprocable therein, a piston rod on which the piston ismounted, sealing means closing one end of .the cylinder about the piston rod to deline with the ,piston a working chamber in the cylinder, means for admitting iluid to the other end of the cylinder, there being a passage through the piston rod from said other end of the cylinder to the working chamber and to the outlet from the pump Vbeyond the sealing means, check valves in said passage `adapted to seat on seats arranged on opposite sides of the part of the passage leading to the working chamber, a floating release pin between the check valves, and a stationary release pin in said other end of the cylinder engageable with one of the check valves when the piston rod exceeds the end of its normal stroke to unseat the last mentioned check valve and through the medium of the floating release pin to unseat the other check valve whereby reverse ow through the .pump can ybe had by moving the piston rod beyond one end of its stroke.

2. A pump comprising a cylinder having an inlet adjacent one end and an outlet adjacent the other, a piston reciprocable in the cylinder, a piston rod by which the piston is reciprocable, sealing means closing the cylinder about the piston rod between the inlet and the outlet and cooperating with the Vpiston to dene a working chamber in the cylinder, a passage in the piston rod open -at its ends to the inlet and outlet respectively and having a port intermediate the piston and sealing means to the working chamber, valve seats in the passage on opposite sides of the port to the working chamber, check valves adapted to seat upon said seats, and means in said passage and in the inlet end of the cylinder for opening both check valves for reverse ilow therethrough when the piston exceeds its normal stroke.

3. A pump comprising a cylinder having an inlet adjacent one end and an outlet adjacent the other, a piston reciprocable in the cylinder, a piston rod by which the piston is reciprocable, sealing means, closing the cylinder about the piston rod between the inlet and the outlet and cooperating with Vthe piston to define a working chamber in the cylinder, a passage in the piston rod open at its ends to the inlet and outlet respectively and having a port intermediate the piston and sealing means to the working chamber, valve seats in the passage on opposite sides of the port to the working chamber, check valves adapted to seat upon said seats, and means in said passage `and in the inlet end of the cylinder for opening both check valves for reverse How therethrough when the piston exceeds its vnormal inta-kestroke.

4. A pump comprising a cylinder 3having an inlet adjacent lone end and an outlet adjacent the other, a piston rod reciprocable in the cylinder having a piston thereon, means providing a seal in the cylinder around the piston rod, said seal and piston defining in the cylinder a working chamber therebetween, .the piston rod having a passage therein open to the inlet end of the cylinder, the outlet from the cylinder and to the Working chamber, a valve seat in the passage between the locations where the passage is open to the inlet .end ofthe .cylinder and Where it is open to the working chamber, a second valve seat in the passage between the location `where it is open yto the Working chamber and Where yit is open to the outlet, valve closures adapted .to yseat .upon .the valve seats, and means in said passage and in the inlet end of the cylinder for opening both valve closures when ,the piston travels beyond its .normal stroke toward the end of the cylinder in which the inlet is located so .as 'to permit of reverse iiow through the valve seats.

5. A .pump .comprising .a cylinder having an inlet adjacent one end and an outlet `adjacent the other, a piston rod reciprocable ,in the cylinder having a piston thereon, means providing a seal in thecylinder around the piston rod, said seal and piston defining in .the cylinder a Working chamber therebetween, the piston .rod :having a passage therein open to the .inlet end of the cylinder, .the outlet from the cylinder and .to the working chamber, a valve seat in the passage :between `the locations where the passage is open to the inlet ,endof the cylinder and where .it-is open to the working-chamber, a .second valve seat inthe passage Vbetweenthe location where it is open to the working .chamber and ywhere .it is open to the outlet, valve closures adapted :to seat upon .the valve seats, a oatin-g Vrelease pin `between ethe `valve Aclosures and a stationary release pin :at the end-of thecylinderin which the inlet is located engageable Iwith the valve .closure that is adapted to seat -on tthe tust-'mentioned valve seat whereby Awhen .the piston travels beyond itsnormal stroke toward the end of the cylinder in which the inlet .is .located both valve closures will be 'openedby the release pins to permit reverse ow through :said passage References Cited ,in the tile of this patentv v5U l\lll.`l ".D STATES PATENTS k880,019 Futhey 'Feb 25, 1908 1,524,159 Sunderman Ian. 27, 1925 1,745,024 1Malone Jan. 28, 1930 2,386,593 Carter Oct. l9, 1945 2,812,129 Adams Nov. A5,1957

2,843,04@ Knowles July 15, y1958 

